The purpose of this study is to examine dispersal behavior of the North American pika (Ochotona princeps), with special regard to its role as an ecological mechanism in colonization and population regulation. Emphasis will be directed toward the behavioral antecedents of dispersal and the characteristics of dispersants. There is a scarity of information relating individual behavioral development to the phenomenon of dispersal. Our primary aim is to collect detailed observations on the behavioral interactions between adults and young (especially parent-offspring conflict) in two local populations, prior to and during colony dispersal. The colony of particular interest inhabits a talus slope near Loveland Pass, 97 km. west of Denver, Colorado. This population presents an unexpected research opportunity for examining the significance of dispersal in colonization. This colony was reduced 65% in November of 1972 during a study of pika territoriality and dominance rank in which autopsy data on the majority of animals were obtained (Kawamichi, 1976). Preliminary data taken in 1976 indicate a failure of the remaining population to regain its previous status. The dynamics of this population will be examined in 1977 (5 years after its depletion) to deteraine its exact number, sex ratio, patterns of movement, and territorial distribution. The second population, located at A-Basin, approximately 2 miles S.E. of Loveland Pass, will be studied as a control with normal population size and density. The study involves live trapping and direct observation, from June through November, 1977. Animals will be ear-tagged for individual recognitio. Pikas are excellent subjects for the study of dispersal. Their diurnal nature and territorial social organization facilitate detailed observation of individuals. No major study has been madeof the behavioral antecedents of dispersal, and the role of parent-offspring conflict in this species.